CXXXVIII. The first Tool in this square is termed a Miter square, of a contrary form to the following, mentioned chap. 9. numb. 17. It hath an Handle (or top part) an Inch thick, and three broad, with a Tongue of the same breadth, and for length 5, 6, or more inches, according to the breadt of the Work: it is to be Glewed into the Handle by a Mortess and Pinned. V. 3 such O. is born by Mitterall.
The second Instrument is a Gage, or square Gage, from the square piece that runs upon the Staff; but of this see more chap. 9 numb. 18. The parts of it are these, the Staff, the hinder end of it; the fore-end in which the Tooth is, the Tooth, and the square or oval, which is that as slips up and down upon the Staff. B. 3 such O. a Chief A. is born by Gagger.
The third is termed a Miter Bar, it is composed of pieces of Wood, of an inch thick each, then nailed together,the one an upright piece, and the other a bottom piece, and on the upright piece, on its upper side are the Miter Lines strucken with the Miter square, from the middle to the right hand, and on the left, which are sawed down to the bottom of the said upright piece. This is a way used by Joyners that make many Frames, to save themselves the Labour of drawing out of Squares, Miters, and several Bevils upon their Stuff.
— From Randle Holme’s “The Academy of Armory, or, A Storehouse of Armory and Blazon” Book III, Chapter VIII, Plate 2.